A Comparison of Different Chemical Sanitizers for Inactivating Escherichia coli O157:H7 and Listeria monocytogenes in Solution and on Apples, Lettuce, Strawberries, and Cantaloupe

Abstract

Ozone (3 ppm), chlorine dioxide (3 and 5 ppm), chlorinated trisodium phosphate (100- and 200-ppm chlorine), and peroxyacetic acid (80 ppm) were assessed for reduction of Escherichia coli O157:H7 and Listeria monocytogenes in an aqueous model system and on inoculated produce. Initially, sanitizer solutions were inoculated to contain approximately 10(6) CFU/ml of either pathogen, after which aliquots were removed at 15-s intervals over a period of 5 min and approximately plated to determine log reduction times. Produce was dip inoculated to contain approximately 10(6) E. coli O157:H7 or L. monocytogenes CFU/g, held overnight, submerged in each sanitizer solution for up to 5 min, and then examined for survivors. In the model system study, both pathogens decreased > 5 log following 2 to 5 min of exposure, with ozone being most effective (15 s), followed by chlorine dioxide (19 to 21 s), chlorinated trisodium phosphate (25 to 27 s), and peroxyacetic acid (70 to 75 s). On produce, ozone and chlorine dioxide (5 ppm) were most effective, reducing populations approximately 5.6 log, with chlorine dioxide (3 ppm) and chlorinated trisodium phosphate (200 ppm chlorine) resulting in maximum reductions of approximately 4.9 log. Peroxyacetic acid was the least effective sanitizer (approximately 4.4-log reductions). After treatment, produce samples were stored at 4 degrees C for 9 days and quantitatively examined for E. coli O157:H7, L. monocytogenes, mesophilic aerobic bacteria, yeasts, and molds. Populations of both pathogens remained relatively unchanged, whereas numbers of mesophilic bacteria increased 2 to 3 log during storage. Final mold and yeast populations were significantly higher than initial counts for chlorine dioxide- and ozone-treated produce. Using the nonextended triangle test, whole apples exposed to chlorinated trisodium phosphate (200 ppm chlorine) and shredded lettuce exposed to peroxyacetic acid were statistically different from the other treated samples.

Effects of Chlorine-Based Antimicrobial Treatments on the Microbiological Qualities of Selected Leafy Vegetables and Wash Water

“…As described above, 10 ppm NaClO was less effective in reducing E. coli O157:H7 on vegetables. Sodium hypochlorite loses its effectiveness on reacting with organic compounds (Inatsu et al, 2005b;Rodgers et al, 2004;Warriner et al, 2003). After using it to wash fresh-cut lettuce inoculated with a high organic load, Baert In addition, Luo et al (2011) explained that when the initial chlorine concentration is low, most chlorine present in the wash solution is consumed in such reactions, leaving little or none for disinfection.…”

Scientific Opinion on the risk posed by pathogens in food of non-animal origin. Part 2 (Salmonellain melons)

“…Melon and watermelon cooled with sanitized water may reduce microbial loads on the outside surface of cantaloupe and honeydew melons by 2-3 logs CFU/melon (Park and Beuchat, 1999;Rodgers et al, 2004). Cooling water may however be a major source of microbial cross-contamination if this is of poor quality.…”

Effects of Nonthermal Processes on the Inactivation of Microorganisms and Antioxidants in Minimally Processed Vegetables

“…Many reports have shown microorganism inactivation effects of GCT and ACT (Puente et al, 1992;Radziminski et al, 2002), with some showing that GCT is more effective than ACT (Sapers et al, 2003;Izumi, 2005). Moreover, the effect of chlorine dioxide treatment on decontamination of vegetables including MPV has been reported (Lee et al, 2004;Rodgers et al, 2004;Gomez-Lopez et al, 2005a). Thus, the chlorine dioxide treatment appears to be a promising method for microorganism decontamination of vegetables.…”